1. Field of the Invention
The present invention relates to a keypad for an electronic device having a metallic texture, and has rigidity and elasticity equivalent to those of stainless steel and allows coloration, and a method for manufacturing the keypad.
2. Description of the Related Art
Portable communication devices generally and enable users of the devices to perform wireless communications with counterpart users. Such portable communication devices include hand-held PCs (HHPs), CT-2 cellular phones, digital phones, PCS phones, and personal digital assistants (PDAs). The portable communication devices can be classified into several types. For example, portable communication devices can be basically classified into a bar-type portable communication device, a flip-type portable communication device, a folder-type portable communication device, and a slide-type portable communication device. Each device is indispensably provided with an antenna unit, data input/output units, and data transmitting/receiving units. The data input unit usually includes a keypad with which data is input by means of depressing buttons via the user's fingers.
The keypad is configured such that as a button portion exposed to outside is pressed, then a dome switch contacts a contact of a printed circuit board for input of various signals.
In the past, the keypad was usually made of soft synthetic resin such as silicon rubber. However, various metal keypads have been developed by substituting a part of synthetic resin with metal, whereby the thickness of the keypad is reduced and an unusual aesthetic sense such as expression of metal's inherent gloss is provided.
As shown in FIGS. 1 through 3, for a conventional metal keypad 1, a pattern of a keypad 3 and a plurality of button portions 3a are formed by performing etching on a metal plate 2 made of stainless steel, and urethane rubber 4 and a silicon pad 5 are bonded to a back surface of the keypad 3.
On the back surface of the keypad 3 is provided a light emitting device (not shown) for emitting light to the button portions (characters and symbols).
To implement various colors on the metal keypad 3, a plurality of coating layers 6 are applied to the metal plate 2.
However, when the plurality of coating layers 6 are applied to the metal plate 2, the metal's inherent texture is degraded because the thickness of the coating layer is about 30 μm.
To solve the foregoing problem, a metal plate made of aluminum may be used. In this case, after the metal plate is anodized, the device itself can be colored, thereby exhibiting metallic texture and a color at the same time.
However, in case of the conventional metal keypad made of aluminum, the material thickness should be about 0.2 mm to secure a sense of clicking and allow etching for the button portions on the back surface. However, there are drawbacks with the aluminum having such thickness as it degrades rigidity and increase susceptibility to deformation.
Accordingly, there is a need for a keypad that can improve rigidity and allow better colorations after anodization.